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Monday, December 12, 2011

I’ve been amazed at just how good the sour beers that have come out of our first three barrels have been. Without the advantage of blending multiple barrels it is fortunate that we have been consistently bottling great beers. We have bottled a total of five batches (not including variants on fruits or dry hops) with another three aging, and not a single clunker.

The solera apple brandy barrel was different from the start though. The barrel was already old when we got it (probably 20 years by my estimate), and displayed the scars of a hard life - a cracked stave and a bit of a vinegary smell. That combination of issues almost caused Nathan and I to search out a replacement barrel, but it held water and smelled alright after a Star-San rinse so we filled it. At eight months in oak the beer was already starting to show signs of going acectic/vinegary. At that point I was considering trying to talk Nathan into pulling the plug and starting over with a “fresh” barrel and beer. Luckily the acetic character calmed down once the ambient temperature dropped, and we decided to let it age a few more months.

At 11 months the beer was very dry (~1.002), oaky, and sharply acidic with a pH of 3.1. In an attempt to reduce the amount of acid production for the first refill we brewed and fermented the fresh beer a few weeks prior to pulling beer from the barrel to reduce the fermentable sugars. Using fermented beer rather than wort does not reduce Acetobacter's acetic acid production (which only requires alcohol and oxygen), but it will reduce lactic acid production. I also like this method because it keeps yeast from building up in the barrel which may eventually lead to autolysis.

With the fresh batch of beer finished fermenting, Nathan and I had to figure out what we wanted to do with the 20 gallons of beer that needed to be siphoned out to make room in the barrel. We left five gallons plain to give us a baseline for comparison of the other version. Despite being just under a year old (relatively young for a sour beer) we pitched rehydrated champagne yeast along with the priming sugar to ensure timely carbonation.

Bottling an amber sour in December, our first through was a fall theme. The night before I halved and roasted two acorn squashes, which weighed about two pounds each. While I love pumpkin, it really is not flavorful enough to come through in a complex beer without using a massive amount. Acorn squash has a distinct sweet/nutty flavor, but we wanted to complement that with warm spices. After talking to Pat Mcilhenney the owner and Brew Master of Alpine Brewing earlier in the week about their wine barrel aged Ichabod pumpkin ale (which includes canned pumpkin puree in the barrel in addition to whole roasted pumpkins in the mash) we took his advice and added cinnamon and nutmeg directly to the fermentor. The baseline for amounts was the two grams of cinnamon and one gram of freshly grated nutmeg I added to the boil for my butternut squash sour brown, but we wanted to make the spices more noticeable. Initially we planned on doubling the spices, but after Nathan weighed and added them to the fermentor seeing the amount gave us cold feet. Luckily spices float so by overfilling the carboy slightly I managed to flush out around half of the spices… I’ll still be tasting it this week.

We dry hopped five gallons with four ounces of Amarillo (about the amount I would use for a DIPA). I am hoping the bright citrusy hop aromatics will meld with the acidity as well as they did in my Amarillo/Simcoe/Cascade bottle hopped sour red. Dry hopped sours are a remarkable rarity given the popularity of both sour and big hop aroma beers, not to mention how many of the breweries that brew great sours also make standout IPAs (Russian River, Lost Abbey, Ithaca, Captain Lawrence, etc…). For the record, I did try to convince Pat to brew a dry hopped sour beer (given their amazingly aromatic hoppy beers), but he said they simply don't have the capacity to store more barrels at this point.

Fruit is always a fun addition (although I was hesitant because it increases acidity), so five gallons went onto six pounds of defrosted blackberries, plus a pound of mulberries. I like blackberries because they add a fruity/winey character that is not as aggressive as raspberries or cherries. This was my first time using mulberries (which are tart and earthy), but in the spring I am planning on harvesting enough from the tree in my backyard to add about two pounds of them per gallon to half of the DCambic.

With 20 gallons of beer removed from the barrel we began to refill it with the fresh beer. The gravity of the new beer was a bit lower than the initial fill, but since the original batches were pretty strong we decided it wasn’t worth screwing around with adding sugar or extract. We ended up with three gallons of extra beer that we’ll use for occasional top-offs to reduce the head space and in turn minimize the acetic acid production. We have not topped-off the other barrels, but for this one it seemed worth the extra effort.

Collected 14 gallons from the first runnings, split between two keggles. Sparged with 15 gallons of ~180 F water, stirred, and used to fill up both keggles. Hops were 2 years old, 15% AA adjusted down.

Ended up with much lower efficiency than I expected.

Chilled both halves to ~74 F. Split between 6 fermentors Aerated each with 30 seconds of pure O2. Pitched Wyeast Farmhouse Ale into 1 fermenter, a total of 3 packs of rehydrated T-58 split between the rest.

12/4/11 Racked the Wyeast Farmhouse carboy into several of the others to harvest the yeast cake for the acid malt soured beer.

12/11/11 Racked into the barrel, three gallons leftover for topping off.
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With regards to dry hopping sours: same as a clean beer? I ask b/c I tried dry hopping a 100% Brett beer with citra hops and felt the hops fired up the yeast again, akin to adding more sugar. A odd experience or do you see similar results?

I don't do anything different than dry hopping a clean beer. Certain strains of Brett produce an enzyme, beta-glucosidase (the same one that breaks down wood sugar), so you could have seen some slow activity from that. However, if it happened quickly it may have just been CO2 coming out of solution.

You mention acetobacter in your post. I am trying to understand how or where the acetobacter is coming from unless you are adding it in your culture. I know it is a naturally occurring bacterium, but why do people always say "have to minimize oxygen due to acetobaacter"? I am especially inquisitive on this regarding those using a WY Roeselare culture which does not contain acetobacter to my knowledge. Is acetobacter or gluconobacter completely unavoidable or is it just that increased oxygen exposure allows the brett to produce more acetic acid which people mistake for acetobacter?

If oxygen can get in, odds are so can Acetobacter (which is all around in the air). If you leave wine open it will turn to vinegar, that is the wild Acetobacter at work. You are right though that if you are just getting oxygen permeation through wood/plastic you shouldn't be getting new bacteria into your beer.

In our case the fact that the barrel had been filled with beer, but was subsequently left empty gave the bacteria a head start. Since Acetobacter is alcohol (~20%) and acid tolerant once it gets in there is no getting rid of it.

Brett will make some acetic acid if given oxygen, but if you are getting a strong vinegar character that is almost certainly Acetobacter.